1. Field of the Invention
The present invention relates to a headlight circuit for an automobile. More particularly, the present invention relates to a circuit that can be used in cars configured for different operating environments.
2. Background and Material Information
Cars for the Japanese domestic market have "ordinary lighting" type headlight circuits (hereinafter "lamp circuits") which light the headlight bulb or high beam bulb when a driver turns a light switch ON. On the other hand, in view of poor ambient lighting, the headlights for cars in Northern Europe must be on during the daytime. These cars use a DRL (Daytime Running Light) circuit that operates the high beam headlight at a reduced power level if (1) the ignition switch is ON, (2) the hand brake is released, and (3) the head lamp switch is OFF. The DRL lamp circuit turns the high beam light off and turns the regular head light(s) on when the light switch is switched ON.
FIG. 3 shows a prior art ordinary lighting lamp circuit 1 for a conventional automobile configured for use in the Japanese market. The lamp circuit 1 includes a left side lamp circuit 1-L and a right side lamp circuit 1-R. In the left side lamp circuit 1-L, wires d1-d9 connect a lamp switch 2 (for ordinary lighting), an ECU (i.e., an electronic control unit) 3, a relay box 4, a junction box 5, a battery 6, a head lamp 7L, and a high beam lamp 8L. Wires d1-d9 are configured in a wire harness for the left side lamp for exclusive use for lighting as a group of wires by bundling the wires d1-d9.
FIG. 4 shows a conventional lamp circuit 1' for DRL. Lamp circuit 1' includes a left side lamp circuit 1-L' and a right side lamp circuit 1-R', similar to ordinary lighting circuit 1. In the left side lamp circuit 1-L', wires d1'-d12' connect a lamp switch 2' (for DRL lighting), an ECU 3', a relay box 4', a junction box 5', battery 6, head lamp 7L, and the high beam lamp 8L. Also, in the right side lamp circuit 1-R', there is a relay box 9' specific to the lighting conditions of DRL. The above electric wires d1'-d12' are configured in a wire harness for the left side lamp for exclusive use for DRL lighting as a group of wires by bundling the wires d1'-d12'.
In the above lamp circuits 1 and 1', various circuit elements are provided exclusively for the different circuits, such that the connections between the each apparatus differ. As a result, the setup of the electric wires to form the appropriate circuit are also different. This in turn requires different wire harnesses and/or assembly procedures for the different connections. This leads to an increase in labor and in manufacturing costs for different kinds of the wire harnesses.